Scripts

Using SetRegionBlocked with a condition didn't work – the computer-controlled hero still passes through the blocked area.

That's quite strange; I haven't encountered this error before. How did you write the code? The SetRegionBlocked function has a parameter that specifies the player number for which the function applies. So, for the second player (whether it's the computer or not):
SetRegionBlocked("region name", true, 2)
If the numbering starts from one, I thought that's how it should be. If it starts from zero, then accordingly:
SetRegionBlocked("region name", true, 1)